The single lamp setup in our sedans is a complicated wiring design, as are most single lamp setups. Thats just due to the 1 bulb having 3 different functions. DRL, LB, HB.
I too am going to be doing this conversion very soon. When you do this, remember that the P5 has a reflector/light (not turnsignal) on the P5 bumper.
As apposed to the sedan which has a reflector/light on the corner of the headlight assembly.
You'll need the reflector/light modified into the corner of the P5 headlight or get a P5 Bumper and run the corner light from the sedan headlight to the spot the P5 Bumper.
Doing this will insure that your vehicle still meets safety standards.